The present invention relates to a booster that boosts a brake operation force with an actuator, and also relates to a brake apparatus using the booster.
Regenerative cooperative control is a known technique used in brake apparatus for vehicles to obtain a desired braking force by controlling the braking force distribution between friction braking using a fluid pressure brake and regenerative braking using a dynamo, e.g. a motor generator. Japanese Patent Application Publication No. 2009-202678 discloses a brake control apparatus including a fluid pressure control unit interposed between a master cylinder and a fluid pressure brake for each wheel. The fluid pressure control unit has a pump, an accumulator, an electromagnetic valve, and so forth to selectively increase, reduce or maintain a fluid pressure to be supplied to the fluid pressure brake. During regenerative braking, the fluid pressure control unit adjusts a fluid pressure to be supplied to the fluid pressure brake, thereby performing regenerative cooperative control.
However, the following problem is associated with a brake control apparatus performing regenerative cooperative control using a fluid pressure control unit as the one disclosed in Japanese Patent Application Publication No. 2009-202678. When the brake fluid pressure is increased or reduced by the fluid pressure control unit during execution of regenerative cooperative control, the fluid pressure in the master cylinder varies. Consequently, the reaction force to the operation of a brake pedal varies, which degrades the brake pedal operation feeling.